1. Field of the Invention
The present invention relates to a method of and a computer product for processing sound segments, and a hearing aid, for improving the sound accuracy heard by a hearing-impaired listener.
2. Description of the Related Art
Because most hearing-impaired listeners (including older adults) have more problems hearing high-frequency sounds, a hearing aid is often used for applying a frequency-lowering process on high-frequency sounds.
U.S. Pat. No. 6,577,739 discloses an “apparatus and methods for proportional audio compression and frequency shifting”, which provides an understandable audio signal to listeners who have hearing loss in particular frequency ranges by proportionally compressing the audio signal. However, this known prior art compresses all audio signals, which may result in serious sound distortion.
U.S. Pat. No. 7,609,841 discloses a “frequency shifter for use in adaptive feedback cancellers for hearing aids”, which improves a conventional frequency shifting method by means of applying frequency shifting only to the high-frequency portion of the signal (which is shifted alternately upward and/or downward), wherein the frequency shifting ratio is less than 6%.
U.S. Pat. No. 7,580,536 discloses a “sound enhancement for hearing-impaired listeners”, which applies frequency shifting to the high-frequency portion of the signal.
U.S. Pat. No. 8,582,792 discloses a “method and hearing aid for enhancing the accuracy of sounds heard by a hearing-impaired listener”, which determines which portion of the high-frequency audio requires a frequency lowering process.
While processing an input sound in real time, a known technique will first divide the input sound into sound segments, and then determine whether to apply a frequency lowering process on each sound segment. In a common case, such as a vowel followed by a high-frequency consonant (e.g., “at”), a conventional technique applies nothing to all sound segments belonging to “a”, and applies the frequency lowering process on all sound segments belonging to “t”; however, the sound between “a” and “t” is usually neither a high-frequency sound nor a low-frequency sound. In this case, if the hearing aid determines that the sound is a high-frequency sound, it will apply the frequency lowering process; otherwise, if the hearing aid determines that the sound is a low-frequency sound, it will not apply the frequency lowering process. However, sometimes it is difficult to classify this kind of intermediate mixed sound, resulting in a rough sound between “a” and “t” while processing “at”. None of the abovementioned known prior art references disclose a solution to this problem.
Therefore, there is a need to provide a method and a computer program product of processing sound segments, and a hearing aid, to mitigate and/or obviate the aforementioned problems.